Safety boom stop



. R m g 9 u N U R w SM n 5 y 2, m WE T mm ,5 r 5 R m WM \w ms 65 EM u wR B E. M S mw mm k vfi sq kw 0 Nov. 7, 1950 Filed Dec. 26, 1945 Nov. 7,1950 F. RUETER SAFETY BOOM STOP Filed Dec. 26, 1945 2 Sheets-Sheet 2 1FIG. 6 FIG. 7

O/iF HO/ST BOOM HO/ST CONTROL INVEN TOR EARLE ERUETER ORNEY Thepresentinventionirelates ..to .stop appara- -tus and. more particularlytoisafety boom stops for rotary cranes. and the like. "a -In the.operation-pf. a. mobile rotary crane it "is "necessary for safetyreasonsto avoid raising 5 ,the pivoted hoist. bonibeyfond a predeterminedheight; 2 Boomi-stops for this: purpose have heretofore been devised,but these. have.:been open :to- Various objections .such as complexityof con- ;struction and relativelvhigh'costof manufacturefl .51 "KAnobject.ofTtheinvention isto'provide an improved safety booms'top-which is of simple and (inexpensive construction arid-readilyapplicable .-.to. existing -m'a"C'hin6SiZ1 I r 'Anotherobject is to"provide a boomistop which is creliable in operation andwhich will notinterfer'e with lthe' lowering f 1 the boomfrom' its=stop'ped'zposition. A "further.'object is to" provide fa boom stopwhich is particularlysuitably'for a loadhandling rmachinei'powereif-iby"an internal combustion 'senginei' 4- 'T The inven ion 'furtherconsi's'ts inthe several features hereinafter-described and claimed. Inthe accompanying drawings, illustrating ecertainiiembodimentsi of the.invention," V

Fig. 1 is a schematic elevational view of a -safety1boom=stopfarrarigedin accordance with the invention;- la't switchiwasing thereof beingshown in 'se'ction'f J 'Fig.v 2is a fragmentary elevational view of the-switch'actuatingmechanism as it appears when -displacedby' the Braisedboom, parts beingshown :in section;.:-. a Fig.1 3 istattran'sversesectionalelevational View :taken generally-alongqthe line 3c3of Fig'. 1;

45..Figz .4iisjaschematic iwiiring' ;.diagram of the .stop'yas appliedIt'OLWgCI'EIlBDhflVlllg anzengine with battery. ignition; I Fig. 5 is aschematic wiring diagram of the stop as applied to a crane having anengine with magneto ignition; Y I

Fig. 6 is an elevational View of a modified form stop switch device,parts being shown in section; 1- Fig. 7 is a sectional elevational viewtaken generally alongthe line 11 of Fig. 6;

Fig. 8 is a schematic wiring diagram of amodi- .fied form of circuit forthe boom stop, and

9 is. a side elevation of .a rotary, crane equipped with a boom stop ofthe invention, parts beingshown schematically. 1 1

V Referring to Figs.,1 toeand '9, the numeral F es n teszse er y a mbile a y 30 "on'the A-frame, as usual.

PATENT: OFFICE i i L iv -Earle-F.;Rueter, Milwaukea wis a'ssignor toUnitv Crane & Shovel Corp" West Allis, Wis., a cor ai enefllel w 1 1 1Application December 26,1 945,"Serial No;631,237

5 Claims. (Cl.212-s9) crane of anyusual/construction. The machineincludes a propelling undercarriage ll, here shown t'olbe of the crawlertype, although'a wheel-type undercarriage may be used, as is wellunderstood in this art. A rotating frame or turntable I 2 is rotatablymounted on the undercarriage and carries the usual mechanism foroperating the machine," this mechanism inroluding a gear-case l3 and anengine or motor One suitable-type of undercarriage "andsoperatingrhechah'ism'is shown inUnited States Patent 2,318,286,-to-Harold E. Brey and Hilbert E; Swan'songfor' Traction BrakeQissued'May-'4, 1943. The engine I4 is connected to the gear- 1c'as'ebyairictionclutch' I5, Fig.1, controlled byiithet'usual actuatinglinkageI5. The gearcase' includes-the usual'bodm-hoisting drum' -l' 'landiload-hoistingdrum- 18, the drum I! being -"rotated in anywellknovvnmanner as by a suitably controlled worm drive 19, Fig. 1. Theturn- "tabIe carriesthe usual A-"frame 20, Fig. 9, and 'also.asuitablecab 2| having a front wall 22 and side wall 23,'Fig. 1'.' v iii A hoistboom'24 is "pivotally connected at' 2'5 topro'jecting supporting parts26 atthe front of the turntable to swing in a vertical plane, and isadjustably elevated by a hoisting cable '21 which is wound on the drumI! and passes over sheaves 28'onthe boom point and sheaves 29 Aload-hoisting cable 30 is-Wound on the jdrum' l8 and passes "oversheaves 3| on' the boom point and over a sheave 32' at a suspendedload-engaging hook 33, as usual. t

5 In accordance with usual practice, the hoisting machine may be readilyconverted to various other forms;'such' as a clam shell, dragline,.iba'ck diggerfla nd excavatingshovel, by providingsu'it'able booms and"other equipment. A

finachine of this t'ype converted to an excavating '45 means areprovided" for limiting the raising of the pivoted boom' 24'."byo-nd'.apredetermined height. The" stopmeanst comprises a control devicedesignated generally by the numeral 34 and adapted to :cooperate'withthe boom, as hereinafter' described. The control device 34'includes acasing 35 adapted to be rigidly mounted on ,th'ei-crane'cab-and-flhavin'g' front and rear Walls with aligned b'.ores;36 in whichis'slidably mount- :ed;.a horizontal :iorwardly projecting ."rod 31withv anabutmentxglisk 38.;at/its exposed front boom at a suitabledistance above the pivot' 2 5 and carries a bolt 45 which is clamped inlongitudinally adjusted position by nuts 46. A roller 41 is carried onthe free end of the bolt and is adapted to abut against the end disk 38of the stop rod 31 to force this rod rearwardly when the boom is raisedto its safe maximum height.

Electric switches 48 and 49 are rigidly secured in the casing and arerespectively disposed below and above the rod 31, each switch beingmounted on a spacer block 58*, Fig; 3. 'These switches in- .cluderespective pivoted plunger-actuatingroller arms 5| and 52, the rollers53 of which bear on diametrically opposite sides of the collar 49, thelatter having a cylindricalsurface 54 and a c'onical cam surface 55. Thetwo switches, or at least the free ends of the roller'arms thereof, arelongitudinally offset so that the switch 48 will operate slightly inadvance of the switch '49'when the cam collar is returned to the'normalposition of Fig. 1 by the spring 42. The 'switches per se are of wellknown construction andpreferably of a snap-action type. urged to openpositionandrequires the application of pressure to its roller arm to'hold it'in -closed position. The switch 49 is of the maintained-contactor. looking type and includes a reset button 55 by which the switch canbe man- The switch 48 is springuallyactuated to closed position, theapplication of pressure to'the'roller arm 52 snapping the &0 switch toits open position. In-theposition'bf the parts shown in-Figs. 1 and 4'the'switch 48 is held closed and the switch 49 is open. The switches 48and 49 are preferably of the double- -throw type, permitting each to beused either as a normally open switch or-anormally closed :switch, theswitch 48 having selectively us'able contacts 48a and 48b-and the switch49 having selectively usable contacts 49aand 4%.

In the present instance, the switches 48 and 49 are connectedin-theignition circuit of the crane engine, the switch 48 being aboom-actuated'limit switch for stopping :the engine when the boom israised to its highest safe position. .In Figs. 1 and 4, the ignitioncircuit is shown to be of the battery type'and includes a battery 51,

manual ignition switch-58g-breaker '59-;with

shunting condenser 60, highetension' coil 8 I with .primary andsecondarywindings anddistributor 82 connected to the engine: sparkplugs'63; all

as usual. The limit switch- 48- is connected'in :series with the manualignition switch. 58,,the

connection being made to theswitch' contact 48a,

Fig. 4. The manually operable switch 49 is connected in shunt to theswitch 48, the connection being'made to the'switchcontact 49a. positionof the parts shownin Figs.- 1 and 4,, the

In the limit switch 48' is held'in closed'position by the cylindricalsurface 54 of the cam collar. 'so' as to completethe ignition circuitand permit operation of the engine. I a

In the operation of the'system of Figs. I and 4,

the raising of the boom to its highest' sa'fe position will push thespring-pressedrod ill-inwardly to the position of ;'2,-l permitting thelimit switch 48 to snap to its open position, thus opening the engineignition circuit and stopping the engine. This serves as a signal to theoperator who then disconnects the driving connection to theboom-hoisting drum [1 and releases the engine clutch- I5. The operatorthen momentarily depresses the reset button 56 of the switch 49 shown.

which locks in closed position andreestablishes the ignition circuitthrough the switch contact 49a, thus permitting restarting of theengine.

: After the engine is again in operation the boom is lowered bymanipulating the usual controls,

permitting the advance of the spring-pressed stop" rod 31 to its normalposition. During this advance, the'limit switch 48 is restored to itsclosed position bythe cam surface acting on the switch arm 5|, andshortly thereafter the switch 49 is restored to its open position by the'ca'm'sur'face 55 actingon the switch arm 52, thus placing the controldevice in condition for a subsequentbo'omstopping"operation. 1"Occasionally, the" boom may be lifted .to "its highest safe positionrby contact with a tree branch or other-obstructionwhile :the crane istravelling. However, thecontrol device will Ifunction'as'ab'ov'edesc'ribedto 'stopfthe engine,

thus immediately stopping the crane and. preventing damage.

"In' the modified form of the invention shown in "Fig.-- 5, the craneengine I 4 is provided with a high-tension ignition magneto 8|. Thisform of magneto is usually 'srendered' ineffective by 'short circuitingorIgrounding-the primary winding, as by a'manual-tswitclr58'. Inapplying the control device to this formeof"magneto circuit,

the switches 48 and 49rare connected in; series by way ofthe contacts-48b and 49b to form-1a shunt around the manual. swit'clr 158'; l' thelimit switch 48 being normally open butz-movable' to :cl'osedposition'upon' the retraction'of-the stop rod' 31 by the -boom, and"there'set switch 149 be- :ingnormally closed but mov'abie to openpositionby the reset button 56 so as to permit restarting *ofthe engine. ':Sincethe: controlswitches 48 and 49 arer of, the double-throwf type, the-same switchesfcanbe used forthe 'circuits ofFigs. 4 and 5 with suitablechanges in the wiring',---as J In the: operation of the-=stopmeans whenarranged as irr Figi: 5,-; the r aising of the-boomto the limit positioncloses the switch48g thuszshortcircuiting the magneto -;;primary windingand stopping the engineq :By: pressing the reset button 56 of the switch-:4 9 v theifiagheto :primarypi'rcuit is reopened, thus permittingrestartingfiof *the engine; A slightloweringzofzthe boom then reopens"the limit switch 48".andrecioses'the switch "49, thereby placing' the'dontrol' 'device' incendi- *tion for; a subsequent boomstoppingioperation.

In the modified form o'frcoiitrbl crevicersnown 42, as inthe device ofFig. 1 The roller si ar-1d- 52"of'theswitehesi ooperate with iihorizontal surfac'e 54 a? l suitable mannen-a's Dy 54 .sec11red 'in theeasin slidable in a and operations-ofthedevice of Figs. 6 and 7 isgtherwise the same as that of Fig. l.

In the modified form of the invention shown ln liig. '8,.the resetswitch 49 is connected in series with an interlock switch 66 which isopened by a .'.b'0om hoist control lever B! when the latter hoistingposition, thus preventing restarting? of, the engine until this controllever is moved outlof hoisting position. The limit switch 48 isfionil'ec ted in a control circuit including the sfv vitjch'contact 48a,a battery 68, and the winding fifljof arelay switch 10, the circuit alsoincludinjg manual switch H. The relay switch controls'l "a suitableengine-enabling circuit here shown to include the battery 68, the relayswitch contacts, a winding 12 ofan enginestop 13, and the manual controlswitch H. U By way of eX-- ample, the engine-enabling circuit may be anignition circuit similar to that of Fig. 4 or Fig. 5. ln the case of acompression-ignition engine, the circuit may control the engineemergency stop, one known type of which functions by shutting off theair supply. The stop is also applicable to control a crane of theelectric motordriven type.

The system ofv Fig. 8 further includes an alarm circuit having thereinone or more alarm devices, such as a bell M and a lamp 15, these alarmdevices being supplied with current by the battery 68 and the alarmcircuit being established through the contact 481) of the limit switch48. In the operation of the system of Fig. 8, the raising of the boom toits highest saie position actuates the limit switch 48', opening thecontrol circuit through the relay winding 69 and closing the alarmcircuit. The relay switch thereupon opens the engine stop circuitincluding the winding 12, causing stopping of the engine or motor. Aftershifting the boom hoist control lever 61 out of hoisting position, theoperator depresses the reset button 56 of the switch 49 to effectclosing of this switch, thereby reestablishing the relay control circuitthrough the then closed series-connected switches 49 and 66. The relayswitch Ill then closes, permitting restarting of the engine. Since theboom hoist control lever is then out of hoisting position, there is nodanger of continued raising of the boom. As the boom is lowered thelimit switch 48 is returned to normal position, thus opening the alarmcircuit and establishing a path for the current flowing through therelay switch windin 69. Shortly thereafter the reset switch 49 opens,placing the device in condition for a subsequentboomstopping operation.

What I claim as new and desire to secure by Letters Patent is:

1. In a load-handling machine having a hoist boom and power means foroperating said boom including control circuit means and a boomhoistcontrol member movable into and out of boom-hoisting position, a limitswitch connected to said circuit means and having a power-enablingposition and a power-disabling position, said limit switch bein normallyin power-enabling position, mechanical means controlled by the boom foroperating said limit switch to powerdisabling position upon the raisingof the boom to a predetermined height and for restoring said limitswitch to power-enabling position upon the lowering of the boom from itslimit position, a manually operable locking-type reset switch connectedwith said circuit means and having an inactive position and apower-enabling position, said reset switch being normally in inactiveposition and being manually operated to power-enabling position whensaid limit switch is in power-disabling position, mechancal meanscontrolled" by the boom for restoring said manuallyoperable reset switchfrom its power-enabling position to its inactive position upon thelowering of the boom from its limit position, and a third switchconnected in circuit with said manually operable reset switch and havinga mechanical actuatin connection with said boomhgistcontrol member forrendering said reset switch ineifective to energize the power meanswhile said control member is in boom-hoisting position.

I2.' In a-safety stop device for a movable power operated member of amachine having power means for operating said member and electriccircuit means for controlling said power means, ar eciprocable membermovable between a normal position and a stopping position, yieldablemeans for normally urging said reciprocable member toward normalposition, said reciprocable member adapted to be mechanically moved inthe opposite direction to stopping position by the movable. member at anend of the travel of said movable'member, a limit switch adapted forconnection with said circuit means and having a powerenabling positionand a power-disabling position, said limit switchbeing normally inpower-enabling position, mechanical means controlled by saidreciprocablemember for operating said limit switch to power-disabling position uponthe travel of said reciprocable member in stopping direction; a manuallyoperable locking-type reset switch adapted for connection with saidcircuit means and having an inactive position and apower-enablingposition; said reset switch beingfnormally in inactive position andbeing manually operable to power-enabling position when said limitswitch is in power-disabling position, and mechanical means controlledby said reciprocable member for restoring said reset switch to itsnormal inactive position upon the return travel of said reciprocablemember to its normal position.

3. In a safety stop device for a movable member of a machine havingpower means for operating said member and electric circuit means forcontrolling said power means, a limit switch adapted for connection withsaid circuit means and having a power-enabling position and apower-disabling position, said limit switch being normally inpower-enabling position, mechanical means controlled by said movablemember for operating said limit switch to power-disabling position uponthe movement of said movable member to a limit position and forrestoring said limit switch to power-enabling position upon the movementof said movable member from its limit position, a manually operablelocking-type reset switch adapted for connection with said circuit meansand having an inactive position and a power-enabling position and beingmanually operable to power-enabling position when said limit switch isin power-disabling position, and mechanical means controlled by saidmovable member in its movement from limit position for restoring saidreset switch from its power-enabling position to its inactive position.

4. In a safety stop device for a movable poweroperated member of amachine having power means for operating said member and electriccircuit means for controlling said power means, a reciprocable cammember movable between a normal position and a stopping position,yieldcam member toward normal position, said cam member adapted to bemechanically actuated'by' said movable member for moving saidreciproca-r ble member in the opposite direction to stopping position atan end of the travel of said movable member, a limit switch adapted forconnection with said circuit means and having a power-enabling positionand a power-disabling position, said limit switch being normally inpower-enabling position, mechanical means controlled by said cam memberfor operating said limit switch to power-disabling position upon thetravel of said cam member in stopping direction, a 'manually operablelocking-type reset, switch ted iorconnectionwvith saidcircuit meansqndhaving an inactive position and a powerenabling position, said resetswitch being normally in inactive position and being manually operatedto power-enabling position when said limit is in powerdisablingposition, and meal means controlled by said cam member iestoring saidreset switch to its normal inactiveposition upon the return travel ofsaid cem member to its normal position.

7 Inasafety stop device for a movable poweroperated member of a machinehaving power for operating said member and electric c rcuit, means forcontrolling said power means, a' casing, a rod reciprocably mounted insaid casing and having a cam, said rod being longitudinally-movablebetween a normal position and a stepping position, yieldable means insaid casing figrnormallyurging said rod toward normal po- Sit/1013 53151rod projecting from said casing and adapted to be longitudinallydisplaced in the opposite direction to stopping position by said mov 8able memberwhen, said movable member approaches an end of its travel, alimit switchirr said casing adapted for connection with said,

circuit means and having a powerrenabling'po sition and apower-disabling position, said limit switch being normally inpower-enabling position, mechanical means controlled by said cam. foroperating saidlimit switch to power-disabling position when said rod ismoved from its normal" position to its stopping position, and a manuallyoperable locking type reset switch in said casing, adapted forconnection with said circuitmeans, and having an inactive position and.a power:-

enabling position, said reset, switch being normally in inactiveposition and being manually operated to power-enabling positionwhencsaidi limit switch is in-poweredisabling position, and, mechanicalmeans controlled by said cam for; rev storing said reset switch to itsnormal position upon the return travel of said rod to its vnormal.

position.

EARLE F. RUETER..

nnrnanncas ci'rEi) Theiollowing references are of record in the fileof'this patent:

UNITED STATES PATE nTs Date

